Catalysts made by the Raney process have been known for many years and have found wide application in the hydrogenation of unsaturated organic compounds such as olefins, acetylenes, aromatic compounds, nitriles, nitrocompounds, aldehydes, ketones, and the like.
The active catalysts are conventionally produced from an alloy of a catalytic metal, such as nickel, with aluminum. The alloy is ground to a fine powder, and the aluminum is removed by leaching with caustic soda solution, leaving finely divided nickel with a surface area of about 10-100 square meters/gram. In this form the nickel, cobalt or other Raney process metal has a great capacity for adsorbing hydrogen, which characteristic gives these catalysts their value.
Catalysts made by the Raney process are generally used in slurry form. The nature of the particles makes packed-column use difficult. In recent years, however, larger granules (e.g., 3-6 mesh, 6-8 mesh, etc.) have become available, permitting limited packed-column use. Such materials are surface-activated and require periodic reactivation resulting in fines.